Backend Staff Engineer

Koinly is a successful product used by crypto investors around the world, helping them make sense of complex portfolios and tax obligations across chains, wallets, exchanges, and Defi protocols. The bar is simple to describe and hard to deliver: a user should be able to reconcile thousands of transactions and file their taxes in under 20 minutes.

We're looking for a Backend Staff Engineer to take deep ownership of our data platform - the engine behind products at the intersection of crypto, finance, and tax. You'll own a high-performance, distributed data-processing backend written in modern TypeScript - the system that ingests, normalizes, and reconciles on-chain and exchange data at scale, and turns it into numbers people file taxes with. Correctness is not negotiable here: a wrong balance is a wrong tax return.

This is a senior, hands-on role for someone who combines exceptional engineering craft with genuine product ownership. We expect you to lead by example: writing high-quality code, making sound architectural decisions, and raising the bar for the entire backend team.

We’re a remote-first, async-first startup with deep product-market fit. If you value autonomy, technical excellence, and clear communication over meetings and process complexity, Koinly is the place for you.

Read on for responsibilities, requirements, and who we are. 👇

Role at a glance

• Mission: Own the distributed backend data engine end-to-end, guaranteeing precision, performance, and scale for complex crypto tax data.

• Location: Remote - Strictly Europe (EU / UK timezones)

  • Note, we won’t review job applications from outside Europe.

• Employment: B2B Contract.

• Compensation: USD $80k – $100k/y.

• Perks: 32 days PTO (incl. public holidays).

• Experience: 8+ years with a focus on complex, data-heavy distributed systems.

🚀 Work within one of the most rapidly growing industries in the world

What we're looking for

We're looking for someone who thrives on complex, business-critical financial systems - architectural depth, high throughput, high-volume ETL, and high stakes. You’ll focus on optimising, refactoring, and elevating our backend architecture while ensuring deterministic execution, high availability, and financial-grade correctness.

Above all, we value a high sense of product ownership, exceptional code quality, autonomy, and openness: you take responsibility for outcomes, not just tasks, and you work independently while staying transparent and collaborative.

We also expect:

• Deep understanding of distributed system architecture and the design patterns that support it at scale - queues, workers, idempotency, backpressure, rate-limiting, and retries.

• Work closely with product and engineering leads, serving as a key technical partner to evaluate ideas, propose architectural solutions, and take real ownership of our backend data pipeline.

• Real, production-level DeFi experience - AMMs, lending, staking, LP positions, and bridges. You understand what on-chain activity actually means, and you can spot data anomalies instantly.

• Advanced data modeling and SQL skills, with a track record of tuning performance on massive PostgreSQL datasets.

• Proven professional experience with Rust - you’ve used it in production or professional settings, can read and write it confidently, and are ready to work in it where extreme performance demands it.

• Fluency with the latest AI development tools such as Claude/Codex/Cursor, and the judgment to put new tools to work effectively in a professional workflow.

Tech stack

You should have deep, production-level experience across our core stack:

Core

• TypeScript (strict, modern) on the Bun runtime, with modern TS tooling (oxlint, Biome)

• Distributed processing with RabbitMQ and Redis (ioredis)

• PostgreSQL - schema design, query optimization, and migrations at scale

• Vitest for unit and integration testing

• Sentry for error monitoring

Data & Blockchain

• Blockchain libraries and node/indexer APIs; RPC and provider reliability patterns

• On-chain data decoding: ABIs, event logs, traces, token standards, transaction semantics

• Data parsing and wrangling: csv-parse, xlsx (SheetJS), node-html-parser

• Integrations against messy, inconsistent third-party APIs and file formats

Infrastructure & Tooling

• PostgreSQL, Heroku, GitHub, JIRA

Nice to have

• Public portfolio of projects available on GitHub or similar platforms.

• Deeper Rust experience, especially in performance-critical data processing.

• Background in financial products, double-entry accounting, or tax domains.

• Familiarity with Ruby (our services interoperate with a Ruby codebase).

• Knows and understands our product.

✔️ Don’t tick all of the boxes? Neither do we 🤷

We're driven by hiring not only by experience and relevance but also by ambition. We celebrate anything ‘outside of the box’, so if you don’t meet every single listed criterion, please do still apply - we’d love to hear from you.

That said, there are two hard gates for this role:

1. Expert-level TypeScript. You should reach for strong typing instinctively, not as an afterthought. We deal with complex financial data where "mostly correct" isn't good enough; your TS skills should reflect that.

2. Deep Distributed Systems & DeFi context. This is a Staff-level role. You need a deep understanding of async queue architectures, idempotency, and how smart contracts execute on-chain. We need someone who can hit the ground running with a complex, high-throughput pipeline.

Why join Koinly as a backend engineer?

• One of the fastest-growing Crypto Tax Calculators in the world with solid product-market fit.

• Trusted and loved: See what our customers say on Trustpilot.

• Direct impact: Our users rely on Koinly for their financial compliance. Every performance optimization and reconciliation engine improvement you ship directly reduces the stress of hundreds of thousands of investors.

• True ownership: We don't believe in "ticket-flipping." You'll own core data services from architecture through deployment and scaling. You have the autonomy to make system decisions that stick.

• High-signal, low-noise: We're remote-first and async-first. We don't do unnecessary meetings or processes for the sake of process. You’ll have long blocks of deep work time to actually build.

🚀 Come and shape the future of crypto tax with us

We aren't just building a calculator; we're building a platform that empowers crypto investors to make the best decisions for their financial future. If you’re ready to own a piece of that journey and build a product people actually need, we want to hear from you.

Our take on Diversity, Inclusion and Belonging

The diversity of our team reflects the diversity of our community and customers. We not only welcome, but celebrate, diverse communities. We feel we have an empowering environment where everyone is supported and respected, and we want you to feel this too. We welcome new ideas, thinking and approaches and listen intently, and we are strongly committed to learning and improving on this as we grow.

Compliance and privacy

Due to our domain, background checks are required before joining. By applying, you consent to processing your data for recruitment purposes per our privacy policy.